3 IZA Discussion Papers
IZA Discussion Paper No. 2893
published in: Teachers College Record, 2011, 113 (7), 1541-1565
IZA Discussion Paper No. 2371
published in: Teachers College Record, 2008, 110, 1613-1640
IZA Discussion Paper No. 671
published in: Applied Economics Quarterly, 49 (1), 2003, 5-22